Transcript Introduction to Science - Mrs. Epperson's Science Classes

Introduction to Science
Unit 1: Chapter 1
1.1 The Nature of Science
Natural Science
Biological
Science
Botany
Ecology
Zoology
Physical
Earth
Science
Science
Chemistry Meterology
Physics
Geology
Critical Thinking
• In science, we use critical thinking.
• What is critical thinking?
• How do we use it?
The Scientific Method
• Step 1: Ask questions.
• At this stage, the only thing a scientist does is
ask questions. Why does my hair get frizzy
on rainy days? Why does popcorn burn after
5 minutes, but not 4 and a half? How do
certain medications affect blood pressure?
The main objective here is to find a topic that
interests you and that can be answered or
solved with an experiment.
• Step 2: Perform research.
• It’s very important that you do step 2 before
step 3. Why? In order for you to form a
hypothesis, you must have some background
information. Research, interviews, and
surveys can help with this process. The more
information you start with, the better your
experiment can be and the more able you’ll
be to analyze your results.
• Step 3: Form a hypothesis.
• As mentioned before, you must have
background info to do this. A hypothesis is
also called an educated guess. This means
that it is a predicted answer or solution based
on prior knowledge, which comes from what
you gathered in step 2.
• We will use the “if/then” format for writing a
hypothesis, which identifies the independent
and dependent variables within an
experiment. (if=IV, then=DV)
• Step 4: Conduct an experiment.
• The fun part! Conducting experiments can
mean many things. For example, sometimes
a simple survey is an experiment.
Observation, testing, and trial and error are
all part of this step.
• This is also a good time to talk about lab
safety, since most experiments will take place
in a laboratory setting.
Lab Safety
• A few reminders when working in the lab:
– No food or drink in the lab unless I specifically tell you
otherwise.
– Always read, re-read, re-re-read instructions, and be sure
to ask questions before you get too far into an
experiment.
– Please be mindful of the fact that there will often be close
to 30 people in the lab with you and that your safety and
theirs is ALWAYS your first concern.
– Familiarize yourself with lab equipment, safety symbols,
and the location of first aid materials before beginning an
experiment.
• Step 5: Analyze data.
• This is the part where you draw graphs, make data
tables, and do calculations. It’s very important that
your recordings are accurate and that your findings
are well organized and easy for others to
understand.
• We will talk more about graphs in a little while.
• Also at this stage, it’s important that you describe
what all your numbers mean. Make sure to label
everything clearly and to interpret the meaning of
your graph or table.
• Step 6: Draw conclusions.
• Though the title simply says to make conclusions,
there are really several components to this step.
• The number one objective in this step is to answer
your original question. Was your hypothesis
supported or will you reject it based on what your
experiment showed?
• Secondary to this is suggesting improvements that
can be made for more accurate results, identifying
factors that might have affected your results
negatively, and tossing around ideas for expanding
on what you discovered.
• Step 7: Repeat.
• In the scientific community, no one will
believe anything you say unless you’ve
conducted the experiment several times and
come up with the same results each time. If
your results should vary, it’s your job to figure
out why and to be able to fix it so that you can
duplicate the experiment with the expected
results and that others can as well.
• Variables - dependent and independent
• The independent variable in an experiment is
the variable that you change and control.
• The dependent variable is the variable that is
changed because of what you are doing.
• For example, the amount of growth in a plant
depends on how much water it receives.
• Controlled experiments are set up so
that only one thing is changed at a time.
• What is the benefit of this?
• If you are manipulating several things at
once, it’s impossible to determine what
is actually causing a specific outcome.
1.2: The Way Science Works
• A major component of any scientific
experiment is collecting data and taking
measurements.
• When scientists take measurements, they
use the metric system.
• It’s important to understand how the metric
system works and its benefits.
• The metric system is useful in science
because:
– It is based on the multiples of the number
10.
– It uses the same prefixes regardless of
what quantity is being measured.
– It is used throughout the world.
– It is easy to convert from one unit to
another.
Units of Measurement
Quantity
Unit
Abbreviation
Length
meter
m
Mass
gram
g
Time
second
s
Temperature
Celcius
C
Current
ampere
A
Amount
mole
Mol
Volume
Liter
L
Prefixes for Large
Measurements
Prefix
Symbol
Meaning
Multiple of
Base Unit
Kilo-
K
thousand
1000
Hecto-
H
hundred
100
Deka-
D
ten
10
*Note: changing units from deka- to kilo- means that you
will divide by 100, not 20.
Prefixes for Small
Measurements
Prefix
Symbol
Meaning
Deci-
d
1/10
Multiple of
Base Unit
0.1
Centi-
c
1/100
0.01
Milli-
m
1/1000
0.001
*Note: changing units from milli- to deci- means that you
will multiply by 100, not 20.
A Helpful Mnemonic Device
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King
Hector
Died
Unexpectedly
Drinking
Chocolate
milk
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Kilo
Hecto
Deka
Unit (m, L, g, s)
Deci
Centi
Milli
Dimensional Analysis:
Conversions
• If you are converting a larger unit to a smaller
unit, you will move the decimal to the right (or
multiply) and end up with a larger number.
• If you are converting a smaller unit to a larger
unit, you will move the decimal to the left (or
divide) and end up with a smaller number.
Practice Problems
• Convert 550 mm to m.
• Convert 3.5 s to ms.
• Convert 1.6 kg to g.
Solutions
• 550 mm = 0.55m
• 3.5 s = 3500 ms
• 1.6 kg = 1600 g
1.3: Organizing Data
• Data is best presented using graphs.
• There are three types of graphs, each of
which can be used for specific
situations.
• A bar graph is best used to compare
similar data for several individual items
or events.
• Line graphs are used to show continuous
change.
• Line graphs contain an independent variable
(the factor that doesn’t change) and the
dependent variable (the factor that changes).
• Pie charts are used to show the parts of
a whole, or the percentages of
individual items or events that make up
the entire item or event.
What do you think?
• Which graph might a company use to
convince a buyer that he/she will see change
(such as hair growth or whiter teeth) if they
buy the product?
• Which graph would show how much oxygen
is present in the atmosphere?
• Which graph would be used to show the
height differences in males versus females
for several different age groups?
Must-Haves
• 5 things every graph must have:
– A title - this needs to be very specific and should include
both the independent and dependent variables.
– A key - this can be a legend to the side of the graph, or
you can label the lines or bars within the graph.
– X- and y-axis labels - the x-axis shows the independent
variable and the y-axis shows the dependent variable.
– Units of measurement - for example, tell if height is
measured in mm or km, if time is measured in seconds or
years, etc.
– An accurate graph - this means the graph needs to be the
proper type and it must make sense.
Significant Figures
• Any time you’re dealing with
measurements, you must have
accuracy and precision.
• Counting significant figures in your
measurements is one way to make sure
that your answer is as precise (exact)
and accurate (close to the actual value
measured) as possible.
The Rules
• 1. ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are
ALWAYS significant.
• 2. ALL zeroes between non-zero numbers are
ALWAYS significant.
• 3. ALL zeroes which are SIMULTANEOUSLY to
the right of the decimal point AND at the end of
the number are ALWAYS significant.
• 4. ALL zeroes which are to the left of a written
decimal point and are in a number >= 10 are
ALWAYS significant.
Examples
• How many significant figures are in the
following numbers?
• 48,923
3,000,000
• 3.967
10.0
• 900.06
501.040
• 0.0004
8.1000
Answers
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48,923 = 5 sig figs (rule 1)
3.967 = 4 sig figs (rule 1)
900.06 = 5 sig figs (rules 1, 2, 4)
0.0004 = 1 sig fig (rules 1, 4)
3,000,000 = 1 sig fig (rule 1)
10.0 = 3 sig figs (rules 1, 3, 4)
501.040 = 6 sig figs (rules 1, 2, 3, 4)
8.1000 = 5 sig figs (rules 1, 3)
Scientific Notation
• A helpful way to check rules 3 and 4 for
significant figures is to write the number
in scientific notation. If you can/must get
rid of the zeroes, then they are NOT
significant.
• Scientific notation is a shorthand
method of writing really large or really
small numbers by multiplying those
numbers by a factor of 10.
Writing in Scientific Notation
Power of 10
Decimal Equivalent
10^4
10,000
10^3
1,000
10^2
100
10^1
10
10^0
1
10^-1
0.1
10^-2
0.01
10^-3
0.001
The Rules
• In scientific notation, the significant figures are
always shown. The trick to shortening the number is
to move the decimal to the space after the first sig fig.
• However many places you moved the decimal is the
exponent that you multiply 10 by.
• If you moved the decimal to the right, the exponent is
negative.
• If you moved the decimal to the left, the exponent is
positive.
Examples
• How do you write the following numbers
using scientific notation?
• 800,000,000
• 0.0015
• 60,200
• 0.00095
• 8,002,000
• 0.00000000006
Answers
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800,000,000 = 8.0 x 10^8
0.0015 = 1.5 x 10^-3
60,200 = 6.02 x 10^4
0.00095 = 9.5 x 10^-4
8,002,000 = 8.002 x 10^6
0.00000000006 = 6.0 x 10^-11